* test(architecture): ratchet top-level layer direction and mutual imports
Declare a layer for every top-level src/ directory and root source file
(domain, contracts, foundation, providers, application, composition,
adapters) in scripts/lib/module-layers.mjs. verify:module-boundaries now also
builds the production import graph between those units and compares it with
a counted baseline: 45 unit pairs import a higher layer (248 imports) and 23
unit pairs import each other. A new upward pair, more imports on a recorded
pair, a new mutual import, or an undeclared unit fails; shrinkage is
reported so the baseline can be lowered.
* fix(architecture): enforce layers for isolated units
